The Financial Industry Regulatory Authority says that Citigroup Global Markets Inc. (C) will pay a fine of $1.85 million for not providing best execution in about 22,000 customer transactions of non-convertible preferred securities, as well as for supervisory deficiencies that went on for over three years. Affected customers are to get over $638,000 plus interest.

A firm and its registered persons have to exercise reasonable diligence to make sure that the sale/buying price the customer pays is the most favorable one under market conditions at that time. FINRA says that instead a Citigroup trading desk used a pricing methodology for the securities that failed to properly factor in the securities’ National Best Bid and Offer. Because of this, contends the self-regulatory organization, over 14,800 customer transactions were priced inferior to the NBBO. The SRO also claims that because Citigroup’s BondsDirect system for order execution used a faulty pricing logic, over 7,200 customers transactions were priced at less than NBBO.

FINRA says that Citigroup’s written supervisory procedures and supervisory system related to best execution in these securities were lacking. It claims that the firm did not review customer transactions for the securities at issue, which were either executed manually by the trading desk or on BondsDirect. Such an assessment could have ensured compliance with Citigroup’s best execution duties. (FINRA noted that it had sent the firm inquiry letters about the reviews.)

Citigroup is consenting to the entry of the SRO’s findings. It isn’t, however, denying or agreeing with FINRA’s claims.